Railway signaling system



Sept. 24, 1940. R. R. KEMMERER 2,215,904

RAILWAY-SIGNALING SYSTEM Filed June 30, 1939 2 Sheets-Sheet l 1-118 ATTORNEY $3 kw. "R5 5% En 5Q m WN UN &

NNN wmmm NN xQ Sept. 24, 1940. R. R. KEMMERER RAILWAY SIGNALING SYSTEM Filed June 50, 1939 2 Sheets-Sheet 2 INVENTOR ATTORNEY Ralph 12. B Y

Patented Sept. 24, 1940 RAILWAY SIGNALING SYSTEM Ralph E. Kemmerer, Swissvale, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a, corporation of Pennsylvania Application June 30, 1939, Serial No. 282,185

In the-above mentioned application there is shown a signal system incorporating at each signal location a lookout circuit which is arranged to effect the supply of steady uncoded energy to the circuit of the adjacent track'section in the rear ,of a signal location in the event that the insulated joint separatingthe track sections in the rear and in advance of the signal location are defective so that energy suppliedto the rear track section feeds overthe defective insulated joint and energizes the track relay of the forward section. I p A As aresultof operationof the lockout circuit shown therein, the trackrelay at the signal location having the defective insulated joint is maintained constantly energized and the signal at that location displays its most restrictive aspect. Similarly, the track relay for the rear section being supplied with steady uncoded energy, conditions the signalwhich it controls to display its most restrictive aspect, hile steady energy is' supplied to th trackv section in the rear of that signal, and so on until an interlocking or other interruption in the signal system, such asspecial cut section-facilities, is reached.

The mode of operation of the signal system shown in the Thompson application in the event of a defective insulated joint creates a safe conditionas it insures that-the signal at the location of the defective joint will display its most restrictive indication, but as the signals throughout the track stretch for a considerable distance in the rear of the defective joint are also conditioned to display their most restrictive aspects, movement of traflic in the track stretch is considerably delayed. A

.As pointed out above, the lookout circuit shown inthe' above identified application is ar- 50 ranged so that on the supply of steady uncoded energy to a track relay steady uncoded current will be supplied bythe lockout circuit associated with that track relay to the track circuit of the adjacent section in the rear. This prevents &5 the use ofsteady energy in a track circuit to discontinue operation of a highway crossing signal, or for other purposes, since if steady energy is supplied to a track circuit for thislpurpose all of the signals in the rear will be caused to display their most restrictive indications even though the 5 track stretch is unoccupied.

It-is an object of this inventionvto provide an improved lockout circuit which will operate in the event an insulated joint is defective to cause the signal at that location to display its most restrictive indication and to supply steady non-coded energy to the track circuit of the adjacent track section in the rear, but which when the track relay is supplied with steady uncoded energy by means in advance of the track relay will not operate to supply uncoded energy to the track circuit of the adjacent tracksection in the rear.

A further object of theinvention is to provide an improved lockout circuit which is non-cas- 2 cadingin operation.

Another object of the invention is to' provide an improved lockout circuitwhich is arranged to supply coded energy to the track circuit of the adjacent track section in the rear for a predetermined period after operation of the track relay is initiated, after which a circuitis established to supply steady uncoded energy to the track section in the rear, the supply of steady energy being interrupted and the supply of coded energy resumed if and only if the track relay continues to follow code, whereby the supply of steady energy to the track section in the rear will be 'continued if an insulated joint separating two sections is defective so that steady energy supplied I to the rear section feeds over the defective joint and maintains'the track relay of "the forward section constantly energized to thereby prevent the operation of the track relay necessary to interrupt the steady energy supply circuit.

A further object of the invention is toprovide an improved lockout circuit for use in a coded signaling system, the lockout circuit being arranged so that it is not established on the first operation of the contacts of the code following track relay, whereby steady energy may be supplied to a track section to effect picking up of the contacts of the track relay of that section without establishing the lockout circuit with the resultant supply of steady uncoded energy to the track section in the rear. 1

Another object of the invention is to provide an improved 1ockout circuit which will make it unnecessary to employ the special cut section facilities heretofore required to prevent the cascading action present when other types of lockout circuits are employed.

Other objects of my invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawings.

I shall describe one form of apparatus embodying my invention, and shall then point out the novel features thereof in claims.

In the drawings, Fig. 1 is a diagram of a stretch of railway track equipped with trafific controlling apparatus embodying my invention, and

Fig. 2 is a diagram of a stretch of railway track including an intersection with a highway together with equipment embodying my invention for controlling operation of signals for protecting the highway crossing.

Construction of the equipment shoumin Fig. 1

- of the drawings Referring to Fig. 1 of the drawings, there is shown therein a pair of track rails l and 2 form.- ing a stretch of railway track over which trafiic normally moves in the direction indicated by the arrow, that is, from left toright. The rails of the track stretch are separated by insulated joints 3 into the customary successive track sections and the rails of each of these sections form a part of a track circuit of the usual character.

The particular track stretch which is represented in Fig. l is intended for use in a railway system employing electric current for propulsion purposes, and for this reason alternating current track circuit energy is used together with impedance bonds 4 of the customary form which conduct propulsion current around each pair of insulated rail joints. As the description proceeds, however, it will be apparent that the apparatus of my invention is equally well suited for use on a steam road in which the application of either direct current or alternating current track circuit energy for control of the signals may be used. In such an application the impedance bonds 4 would of course be omitted.

In the diagram forming Fig. 1 two complete track sections are shown, these being identified as sections HT and HT. Each of these track sections has located at the entrance end thereof a signal for governing movement of trains in the track stretch, the signal for section EIT being identified as HS, and the signal for section I2T being designated IZS. The signals illustrated are of the familiar color light type having a green or clear lamp G, a yellow or caution lamp Y, and a red or stop lamp R.

While this invention is illustrated and described in connection with a signal system employing wayside signals, it should be understood that the invention is applicable. also to a signal system having cab signals only. I

The rails of each of the track sections form a part of a track circuit to which coded alternating current train control energy is supplied at the exit or leaving end from the secondary of a track transformer TT with a prefix corresponding to that of the associated track section. The circuits for supplying current from the track transformers TT include the usual current limiting reactors RA. The energy supplied to the track circuits is derived from any suitable source and may be distributed throughout the track stretch by a transmission line, not shown. In the drawings the reference characters BX and CK designate the terminals of such power supply source and it will be assumed that the energy supplied from this source is alternating current with a frequency of 100 cycles per second.

Each of the signal locations has associated therewith a suitable source of direct current, such as a primary or a storage battery, not shown, the terminals of which are designated in the drawings B and C.

The particular signaling system, shown in Fig. 1 is of the three-indication variety and it makes use of track circuit energy of two different codings. This coded energy is provided by code transmitters CT which interrupt the supply circuit of the associated track transformer a definite number of times per minute according to trafiic or other conditions ahead. In the illustrative form shown each code transmitter CT is provided with two circuit making and breaking contacts 80 and I80 which are continuously actuated by a motor or other suitable mechanism at two different speeds. For purposes of illustration it will be assumed that these speeds are suchas to provide 80 and180 energy impulses per minute which are separated by periods of equal duration in which no energy is supplied.

Each of the track sections includes a track relay designated 'I'R together with an appropriate prefix, while the track relay is located at the entrance end of the track section with which it is associated. The track relays may be of any suitable type, and as shown are of the direct current type having their windings connected to the track rails of the associated track sections through suitable resonant units RU shown diagrammatically in the drawings.

The resonant units RU each comprise a transformer, a capacitor and a reactor so arranged and proportioned as to freely pass the 100 cycle coded signal control energy, but so as not to pass propulsion current of a difierent frequency, while a rectifier is incorporated in each unit to convert into direct current the alternating current which is supplied through the unit.

The track relays TR are provided with contacts l5 and i6 which when the relay winding is deenergized occupy their lower or released positions, as indicated by dotted lines, while when the relay winding is energized, the contacts I 5 and I6 occupy their upper or picked up positions, as shown. I I h Each of the track relays has associated therewith two front contact repeater relays FSA and FSB, two back contact repeater relays BSA and BSB, and two signal control relays J and H. j

The apparatus associated with the signals HS and I 2S are duplicates of each other and accordingly only the apparatus at signal'lZS will be described in detail. Referring to the equipment at signal Us, the contacts I5 and I6 of the relay l2TR are connected by wire I! to terminal B of the local source of direct current. Contact [6 when released engages a back contact l8 which is connected by wire 20 to contact 2| of relay I2FSB and to one terminal of snubbing resistor 23 associated with relay IZBSB. Contact 2! of relay IZFSB when picked up engages a contact 24 which is connected by wire'25 tdone terminal of the winding of relay I2BSB, the other terminal of which is connected to a terminal of snubbing resistor 23 and to terminal C of the local source of direct current. Contact 2| of relay IZFSB when released engages a contact 2'! which is connected by wire 28 to contact 29 of relay IZFSA, while relay I2FSA has a contact 30 which when picked up engages contact 29.

Contact 39 isconnected by wire 32 to one'terminal of a snubbing resistor 34 and also to one terminal of the winding of relay I2BSA. The other terminals of the resistor 34 and of the winding of relay I2BSA are connected to terminal C of the source of current.

When contact I6 of relay I2TR. is picked up, it engages a contact 36 which is connected by wire 38 to contacts 39 and 42 of relay=I2FSB, to one terminal of snubbing resistor 49 associated with relay -IZFSB, to contact M of relay I2BSA, and to contact 43 of relay I2I-I. 7 'Contact 39 of relay I2FSB when released engages a contact 45 which is connected by wire 46 to one terminal of the winding of relay IZFSA, andalso to one terminal of snubbing resistor 41 associated with the relay IZFSA. The other terminals of the relay winding and of the resistor 41 are connected to terminal C of the source of current.

Contact 39 of the relay IZFSB when picked up engages a contact 49 which is connected by wire '59. to contact 5|, while relay IZBSB has .a contact 52 which when picked up engages contact Contact 52 is connected by wire 54to one terminal of the winding of relay I2F'SB; the other terminal of which is connected to a'terminal of snubbing resistor 40 to terminal 0 of the source of current.

, Relay IZBSA has a contact 55 which when picked up engages contact 4|. Contact 55 is connected by wire 51 to contact 58 of relay I2H, while a branch of wire 51 is connected to contact 59 of relay I2FSB. Contact 59 when picked up engages a contact 42, while relay IZH has a contact 60 to which is connected a branch of wire 54 and which when released engages contact 58. Relay I2I-I has a contact 62 which when released engages contact 43 and which is connected by wire 64 to contact 65. Relay I2BSB has a movable contact 66 which when picked up engages contact and which is connected by wire 61 to a terminal of the winding of relay I 2I- I the other terminal of which is connected to terminal C of the source of current. A snubbing resistor I0 is connected across the terminals or the winding of relay I2I-I. I Contact 62' of relay I2I-I when picked up engages contact II which is connected by wirelZ to terminal B of the local source of current. v The relays IZFSB, I2BSB, and IZI-I have contacts which control the circuit. of the primary winding of track transformer IITT. One tor..- minal of theprimarywinding I4 of the track transformer is connected to terminal CX of the source of 100 cycle alternating current, while the other terminal of the winding I4 is connected by wire I5 to contact I6 of relay IZESZB and to the 89 code contact of coding relay IZCT.

Contact I6 when picked up engages a contact 11 which is connected by wire 18' to'contact' I9 of relay IZBSB, and to contact 82 which is .en gaged at times by contact of relay I'ICT.

Contact I9 of relay IZBSB when released engages contact 84 which is connected by wire. 85 to terminal BX of the source of ,alternatingycurrent, while contact I9 when picked up engages contact 81 which'is connected by wire 89 to contact 90 of relay IZI-I. Contact 90 when picked up engages contact 92 which is connected by wire 93 to contact 94, which is intermittently engaged by contact I80 of coding relay I2CT. Y J The relays I2J and I2I-I have contacts-which control the circuits of the lamps of signal IZS. The relay I2H has a contact 95 whichis' connected by wire 96 to terminal B of the local source of current; Contact '95 when released engages contact 91" which isconnected by wire 98 to one terminal-of the lamp R, the other terminal of which'is connected by wire I90 to terminal C of the local source of current. As-long asccontact 95 of relay IZH is released, a circuit is established to illuminate'thered or stop lamp R of signal I2S'. When contact 95 of relay IE8 is picked up, the circuit of lamp R is interrupted, while contact 95 engages contact Illl which is connected by wire I92 to contact I93'of relay IZJ. Contact I03 when released engages contact I04 which is connected byrwire I95 to one terminal ofthe yellow lamp Y, the other terminal of which has a branch of wire I99 connected thereto. Accordingly, when contact 95 of relay IZI-I is picked up and contact. I93 ofrelay I2J is released, a'circuit isestablished to illuminate the yellow. or caution lamp Y of signal IZS;

When contact IIi3-of relay I2J is picked up, it interrupts thecircuit of the lamp Y, while it engages a contact iii'i which is connected by wire 108- to one terminal of lamp G, the other terminal of which has connected thereto a branch of wire I09. Accordingly, when contacts 95 and I93 are both picked up, a circuit is established to illuminate the green or clear lamp G of signal I2S. As pointed out above, the equipment associated with signal IIS is a duplicate of that associated with signal IZS so it is unnecessary to repeat a description of the construction of this apparatus.

The equipment is shown in Fig. 1 of the drawings in the condition which is assumes whenthe sections IIT and HT are both unoccupied, and when there is at least one unoccupied section in advance of section I2T with the result that coded current of the 589 code frequency is supplied by transformer I2TT to the track circuit of track section I2T.

As section IZTis supplied with current of I99 code frequency, the contacts of the track relay I2TR will'be picked up and released periodically in accordance withthis code frequency.

During the picked up periods of the relay contacts, contact 56 establishes a circuit to energize the winding of relay IEF'SB, this circuit being traced from terminal B of the source of current through wire I'I, contacts Iii-35 of relay IZTR, wire 38, contacts 39-49 of relay IZFSB, wire 50, contacts 5I-52 of relay IZBSB, wire 54, and winding of relay IZFSB to terminal C of the source of current. As the winding of relay IZFSB is energized, the relay contacts are picked up.

In addition, at this time the snubbing resistor 40, which is connected between wire 39 and terminal C-of the source ofcurrent, is shunted across the terminals of the winding of relay IZFSB with the result that the relay contacts are rendered slow in releasing. The contacts of relay I2FSB, therefore, remain picked up during the released periods of the contacts of the code following track relay 52TH, during which time no energy is supplied to the winding of relay I2FSB.

During the released periods of the contacts of track relay IZTR, a circuit is established to energize the winding of relay I2BSB. This circuit is. traced from terminal B of the sourceiof current through wire-ll, contacts Iii-4B of. relay EETR, wire 29, contacts 2I24 of relay I2FSB, wire 25, and winding of relay IEBSB to terminal C of the source of current. As the winding of relay I2BSB is energized, the contacts of the relay are picked up. At this time the snubbing resistor 23 is shunted across the winding of relay IZBSBI with the result that the relay contacts are slow in releasing and remain picked up during the picked up periods of the track relay contacts.

At this time the winding of relay [2H is energized by current supplied over a circuit which is traced from terminal B of the source of current through contacts II-62 of relay IZI-I, wire'64, contacts 65-66 of relay IZBSB, wire 61, and winding of relay I2H and snubbing resistor I0 in parallel therewith to terminal C of the source of current. As the winding of relay I2I-I is energized, the contacts of the relay are picked up, and as the snubbing resistor I0 is shunted across the relay winding, the contacts of the relay are slow in releasing.

As the track relay IZTR is following code of the I code frequency, its contact I5 alternately engages contacts I I 0 and I I2 which are connected by wires H4 and H5 to the resonant unit RUA. On operation of the track relay contact at this frequency the resonant unit I2RUA is effective to energize the winding of relay IZJ with the result that the contact I03 of relay I2J is picked up.

As contact of relay IZH and contact I03 of relay I2J are picked up, the circuit to energize the green lamp G of signal IZS is complete, and this lamp is illuminated to indicate that there are at least two unoccupied blocks in advance of the signal.

As the contacts of relays IZH, IZBSB, and I2FSB are picked up, a circuit is established to supply the primary winding 14 of track transformer IITT with energy periodically interrupted by the I80 coding contact of code transmitter I2TT. This circuit is traced from terminal BX of the source of alternating current through contacts I8094 of code transmitter CT, wire 93, contacts 92-90 of relay I2H, wire 89, contacts 81-19 of relay IZBSB, wire 18, contacts IT-I6 of relay IZFSB, wire I5, and primary winding 14 of track transformer IITT to terminal CX of the source of alternating current.

Accordingly current of the I80 code frequency is supplied by the secondary winding of track transformer IITT to the track circuit of track section I IT, while the equipment associated with signal IIS is conditioned to illuminate the green lamp of signal IIS and to supply energy of the I00 code frequency to the adjacent track section in the rear, that is, to the track section IOT.

At this time as contact 39 of relay IZFSB is picked up, it interrupts the circuit of the winding of relay IZFSA, while as contact 2I of relay IZFSB is picked up, it interrupts the circuit of the winding of relay IZBSA.

The circuit of the winding of relay IZBSA is additionally interrupted by contact 30 of relay I2FSA which is released at this time. It will be seen, therefore, that at this time the relays IZF'SA and I ZBSA are deenergized and their contacts are released.

In similar manner the relays I IFSA and I IBSA are deenergized and their contacts are released.

Operation of equipment shown in Fig. 1 on passage of a train If while the equipment is in the condition shown, a train moving from left to right enters the track section I IT, the equipment on the locomotive will receive current of the I80 code frequency and the cab signal apparatus carried thereby will respond to current of this frequency to give a clear indication.

When the locomotive enters the track section I IT, it shunts the track relay I ITR with the result that this relay no longer responds to the coded energy supplied to the track rails'of the track section by thetransformer IITT, and the contacts of the relay IITR remain in their released positions.

As the contact I6 of relay IITR does not engage its front contact, the circuit for energizing the .winding of relay IIFSB is not established and the contacts of relay I IFSB become released after the expiration of a time-interval determined by the release time of the relay.

On shunting of thetrack relay IITR. the contact I6 thereof becomes released if it is not already in that position thereby completing the circuit for energizing the relay I IBSB. However, as soon as the contacts ofrelay IIFSB become released, contact 2| of relay IIFSB interrupts the circuit forenergizing the winding of relay IIBSB, while this contact when released also opens the circuit by which snubbing resistor 23 is shunted across the winding of relay IIBSB. Accordingly on release of contact 2| of relay IIFSB relay IIBSB is deenergized, and the contacts thereof quickly become released.

On release of the contacts of relay I IBSB contact 66 interrupts the circuit of the winding of relay IIH, and after a brief time interval the contacts of relay II H become released. On the release of contact 95 of relay IIH the circuit for energizing the green lamp G of signal IIS is interrupted, and the circuit for energizing the red lamp R of the signal is complete so the signal now displays its stop indication.

When the track relay I I'I'R, is shunted and no longer follows code its contact I5 remains in engagement with its back contact I I2 and does not intermittently engage contact IIO with the result that resonant unit IIRUA is no longer effective to supp-1y energy to the winding of relay I IJ. Accordingly relay 1 IJ becomes deenergized and its contact I03 becomes released. Because of the inherent characteristics of the resonant unit I IRUA, relay I I J does not release instantaneously on cessation of operation of contact I5 of relay I ITR and contact I03 remains picked up for a brief time interval. As a result, contact I03 may remain picked up until after contact 95 of relay IIH becomes released to interrupt the circuit for energizing the green lamp G.

If, however, contact I03 becomes released before'contact 95 becomes released, the circuit for energizing the green lamp G will be interrupted, while contact I03 will establish the circuit to energize the yellow lamp Y. On subsequent release of contact 95 of relay I IH the yellow lamp will become extinguished and a circuit to illuminate the red lamp will be established. This brief flash of the yellow lamp is not objectionable since it does not occur until after the locomotive has passed the signal I IS.

On release of contact I6 of relay I I F'SB the circuit' for supplying energy of I80 code frequency to the primary winding 14- of .track transformer I0'IT is interrupted, while on release of contact I9 of relay IIBSB a circuit is established to supply current of 80- code frequency to the primary Winding 14 of track transformer IOTT.

This circuit is traced from terminal BX of the source of alternating current through wire 85,

contacts 8419 of relay IIBSB, wire I8, contacts 82-80 of code transmitter I ICT, wire I5, primary winding 14 of track transformer IOTT, and terminal UK of the source of current.

As the 'train continues through the track the winding of relay stretch and enters track section I2T, it shunts the trackrelay I2TR, and the equipment associated with this track relay operates in the manner described in detail in connection with section IIT to cause the signal IZS to display its red or stop indication, while the supply of current of I80 code frequency to section HT is cut off, and current ofthe 80 code frequency is supplied to iiheprimary winding 14 of track transformer ITT.

As long as any portion of the train remains in track section IIT, the track relay IITR is shunted and does not follow the current of 80 code frequency supplied by the track transformer IITI'.

' When the train advances far enough in the track stretch that the rear of the train passes out of the track section IIT, the track relay IITR is no longer shunted and its contacts become picked up and-released in response to current of the 80 code frequency supplied by track transformer II'I'I. I

v On the first picked up period of the contacts of the track relay I ITR which may be considered the first operation'of the relay contacts, contact I6 establishes a circuit to energize the winding of relay IIFS'A. This circuit is traced from terminal- B ofthe source 'of current through wire I'I, contacts I6-3B of relay IITR, wire 38, contacts 39-45 of relay IIFSB, wire 46, and winding of relayll IFSA and snubbing resistor 41in parallel to terminal of the source of current.

As a result of energization of the winding of relay IIFS'A, the contact 30 of this relay becomes p'ickedup and establishes the circuit for energizing the winding of relay IIBSA, and on the first released period of the contacts of relay I ITR. the circuit for energizing the winding of relay I IBSA is complete.

On the first released period of the contacts of the track relay IITR following the first picked up period, which may be considered the second operation of the relay contacts, contact I6 engages contact I8 andestablishes the circuit for energizing the winding of relay I IBSA. This circuit is traced from terminal B of the source of current through wire-I1, contacts IB-IB of relay IITR, wire 20, contacts 21-21 of relay IIFSB, wire 28, contacts 29-30 of relay IIFSA, wire 32, and winding of relay IIBSA and snubbing resistor 34 in parallel to terminal C of the source of current.

As a result'of energization of the winding of relay I IBSA, contact 55 of this relay becomes picked up and establishesa pick-up circuit for the winding of relay IIFSB so that relay IIFSB is energized on thenext picked up period of the contacts of the relay I ITR, which may be considered as the third operation of the relay contacts.

' The circuit for energizing the winding of relay I IFSB is traced from terminal B of the source of current through wire I'I, contacts Ifi-SB of relay IITR, wire 38, contacts 4I-55 of relay IIBSA, wire 51, contacts 58-60 of relay III-I, Wire. 54 to IIFSB, the other terminal of which is connected to terminal C of the source of current. v

It will be seen that connection is established from wire '38 to one terminal of the winding of relay IIFSB, while wire 38 is directly connected to one terminal of snubbing resistor 4%], and that the other terminal of the snubbing resistor 40 is "connected to the other terminal of the winding of relay I IFSB. As a result, the snubbing resistor 40 is shunted across the winding of the relay and stick circuit for the winding of relay renders the relay contacts slow .in releasing with the result that these contacts will be maintained picked up during brief periods in which the energizing circuit of the relay winding is interrupted bythe track relay contacts.

As a result of energization of the winding of relay IIFSB, the contacts of this relay become picked up and interrupt the previously traced circuit for energizing the windings of relays I IFSA and .I IBSA, while on picking up of contact 16 of relay HFSB the lookout circuit for this track section is established and steady energy is supplied to the primary winding 14 of the track transformer IfiT of the adjacent section in the rear. The lockout circuit for supplying steady energy istraced from terminal BX of the source of alternating current .thorugh wire 85, contacts 84-19 of relayv I IBSB, wire I8, contacts IT-l6 of relay IIFSB, and wire 15 to one terminal of the primary -winding .14 of track transformer "ET, the other'terminal of which is connected to terminal CX of the source of current.

If the contacts of the track relay IITR continue to follow code then on the next or fourth operation of the relay contacts, which is their second released period, acircuit is established to energize the winding'of relay IIBSB. "This circuit is traced from terminal 3 of the source of current through wire. I'I, contacts IIi-IB of relay ,I ITR, wire. 20, contacts 2I-24 of relay 1 IFSB, wire-25, and winding of relay IIBSB to terminal C of the source 'ofcurrentl In addition, it will be seen that wire is connectedtoone terminalof the snubbing resistor 23, the other terminal of which is connected to a terminal of the winding of relay IIBSB with the result that the snubbing resistor 23] is shunted across the relay winding to render the relay contacts slow in releasing.

On picking up of the contacts of relay IIFSB contact 59 engages contact 42 to establish a circuit through which current maybe supplied to the winding of relay IIFSB during the picked up periods of the track relay contacts. This prevents deenergization of the winding of relay IIFSB on opening of contact 55 ofrelay IIBSA. In addition, on picking up r-of the contacts of relay I IFSB contact 39 of the relay engages contact 49 to establish a stick circuit for the winding of relay IiFSB, this circuitlbeing completed on picking up of contact 52 of'relay IIBSB. The IIFSB is traced from wire 38 through contacts 39-49 of relay IIFSB, wire 50, contacts 5l-52 of relay IIBSB, wire 54, winding of relay I IFSB, and terminal C of the source of current. It will beseen also that at this time snubbing resistor 40 is shunted across the winding of relay IIFSB so that the contactsof ,the relay are slow increleasing and will bridge over the released periods of the contacts of track relay I I TB. e

In addition, on picking up of the contacts of relay HBSB contactGB establishes a circuit for energizing the winding of relay III-I, this circuit being complete on the third'picked up period of the track relay contacts, that is, the fifth operation of the relay contacts. This circuit is traced from terminal B of the source of current through sufficient magnitude to cause the relay contacts to become picked up, and on picking up of contact 02 of the relay the previously traced circuit for energizing the relay winding is interrupted, while contact 62 engages. contact II to establish 'a stick circuit for maintaining the relay winding energized as long as contact 66 of relay IIBSB remains picked up.

On picking up of contact 19 of relay 1 IBSB the previously traced lockout circuit for supplying steady energy to the primary winding 14 of track transformer IOTT .is interrupted, while on picking'up of contact of relay IIH a circuit is established to supply current of the I80 code frequency to the track transformer IIITT. This circuit is traced from terminal BX of the source of current through contacts I80-94 of code .transmitter IICT, wire 93, contacts 9290 of relay Ill-I, wire 09, contacts 8'I'I9 of relay HBSB, wire 18, contacts 'I116 of relay IIFSB, wire I5, and primary winding 14 of transformer IOTT to terminal CX of the source of current.

' As a result of the supply of current of I80 code frequency to the track circuit of the section IOT, the signal associated with that section will display its clear aspect to indicate that there are two funoccupied blocks in advance thereof.

As a result of operation of the contacts of relay ,I ITR in response to current of 80 code frequency, contact I5 alternately engages contacts H0 and H2, but the frequency of the current supplied to the resonant unit IIRUA is not such as to cause this unit to pass suflicient current to energize the winding of relay I IJ. Accordingly contact I03 of this relay remains released, while as contact of the relay IIH is picked up, the circuit for illuminating the red lamp R of signal HS is interrupted and the circuit for illuminating the yellow lamp Y of the signal is complete.

When the train advances far enough in the track stretch that the rear of the train enters the section in advance of section I2T, that is section I3T, the equipment associated with that section is conditioned to supply current of the 80 code frequency to the track circuit of section IZT. When the train advances far enough in the track stretch that the rear of the train passes out of the track section I 2T, the equipment associated with that section operates in the manner described in detail in connection with the equipment associated with section IIT to supply coded current of the I80 code frequency to the I track circuit of section HT.

On the supply of current of the I80 code frequency to the track circuit of section IIT the contacts of the track relay II TR follow this code and the relays IIFSB, IIBSB and IIH remain energized, while resonant unit I IRUA now passes sufficient current to energize the winding of relay IIJ. Accordingly contact I03 of relay IIJ becomes picked up and interrupts the circuit of the yellow lamp Y of signal HS, and completes the circuit to illuminate the green lamp G of signal 'IIS.

Atthis time as current of the I80 code frequency is already being supplied to the section I I 0T, no change is made in the code frequency.

As the train continues its movement through the track stretch and clears the section I3T in j advance of section I2T, the apparatus associated with that track section effects the supply of current of I80 code frequency to the track cir- -cuit of section I2T and relay IZJ thereupon becomes picked up with the result that the green lamp G of signal I2S is illuminated.

ment in the event an insulated joint-separating two tracksections considered. 7 i I Operation of equipment shown in Fig. 1 the event of a defective insulated y'oznt For purposes of illustration, it will be assumed that an insulated joint separating sectionsIIT and IZT breaks down as a result of passage-of a train through the track stretch sothat energy supplied to the track circuit of section IIT may feed over the defective insulated 'joint and energize the track relay IZTR of section I2T.

When the train enters section IZT, it shunts the track relay IZTR and the equipment associated with the relay operates as described in detail above to supply current of the 80 code frequency to the primary winding of track transformer .I I TT.

As long as a portion of the train remains in section IIT, the track relay of' -that section is shunted, while the track relay of section I2T will continue to be shunteduntil the train has advanced far enough in the track stretch that the rear of the train is located a substantial distance in advance of the point of connection of the relay IZTR with the rails of section IZT;

When the rear of the train vacates section HT, the track relay IITR is no longer shunted and follows the coded current supplied to the track is defective will now be 'circuit, and the equipment associated with the distance beyond the point of connection'of the winding of track relay IZTR with the; rails of section IZT, the potential between the rails resulting from the rear section leakageenergy which feeds over the faulty joint rises to a value sufiicient to efiect code following operation of the relay IZTR.

On the first operation of the contacts of relay IZTR, that is, the first picked up period of the contacts of the relay, a circuit is established'to energize the winding of relay I2FSA. This circuit is traced from terminal B of the local source of current through wire I1; contacts IS-36 of relay IZTR, wire 38, contacts 3945 of relay IZFSB, wire 46, and winding of relay I ZFSA and snubbing resistor 41 in parallel to terminal C of the source of current.

On the second operation of the contact l6 of relay IITR, that is, the first released period of the relay contacts, contact I6 engages contact I8 and establishes a circuit to energize the winding of relay I2BSA. This circuit is traced from terminal B of the source of current through Wire I'I, contacts I6I8 of relay I2TR, wire 20, contacts 2I-2'I of relay IZFSB, wire 28, contacts 29-30 of relay I2FSA, winding of relay I 2BSA, and snubbing resistor 34 in parallel to terminal C of the source of current.

As a result ofenergization of the winding of relay I2BSA, contact 55 of the relay becomes picked up and establishes a circuit through which current is supplied to the winding of relay IZFSB on the next, or third operation,-0f the contacts of relay I 2TR. On this third operation of the relay contacts, contact I6 is picked up and engages contact 36, while the circuit for energizing the winding of relay IZFSB is traced from ter- 75 minal. B of the source of current through wire I1, contacts I636 of relay IZTR, wire 38, contacts 4I-55 of relay IZBSA, wire 51, contacts 5860 of relay IZH, wire 54, and winding of relay I2FSB to the terminal B of the source of current.

n energization of the winding of relay IZFSB contact I6 of the relay becomes picked up and establishes the lookout circuit for supplying steady uncoded energy to the primary winding 14 of track transformer IIT'I. This circuit is traced from terminal BX of the source of a1ternating current through wire 85, contacts 84-49 of relay IZBSB, wire I8, contacts 11- -16 of relay .19 of relay IIBSB,.the

IZFSB, and wire 15 to one terminal of the transformer primary winding, the other terminal of which is connected to terminal OX of the source of current. i

As a result of the supply of steady uncoded energy to the track circuit of section III, steady energy feeds over the defective insulated joint separatingsections HT and IZT and maintains the track relay IZTR energized with the result that contact I6 continues to engage contact 36.

On picking up of the contacts of relay IZFS-B contact 59 establishes a stick circuit to maintain the relay winding energized after release of the contacts of relay IZBSA. This stick circuit is traced from wire 38 through contacts 42-59 of relay IZFSB, wire5'l, contacts 58-60 of relay IZH, and wire 54 to one terminal of the winding of relay IZFSB, the other terminal of which is connected to terminal C of the source of current On picking up of contact 2 I of relay I2FSB, the circuit for energizing the winding of relay IZBS A is interrupted and the contacts of that relay become released.

It will be seen, therefore, that on this the third operation of the contacts of relay IETR, the lockout circuit for supplying steady energy to the adjacent track section in the rear is establi'shed, and is maintained as long as contact I6 of relay IZTR remains picked up, which contact will remain picked up as long as steady energy continues to be supplied to the adjacent track section in the rear and feeds over the defective ilnsulated joint to energize the winding of relay On the supply of steady energy to the track circuit of the section IIT at a time when energy of the 80 code frequency has previously been supplied thereto, the contacts of the track relay I ITR are held picked up, and contact I6 does not intermittently engage contact I8 to effectthe supply of impulses of energy to the winding of relay IIBSB.

Accordingly after a brief time interval which is determined by the release time of relay I IBSB,

the contacts of this relay become released and contact 52 thereof interrupts the circuit for energizing the winding of relay IIFSB, while contact 52 also interrupts the circuit by which the snubbing resistor 48 is shunted across the winding of realy IIFSB. As a result the contacts of realy I IFSB quickly become released and contact 16 of relay IIFSB'interruptsl the circuit through which coded current of the I80 code frequency was supplied to the track transformer IEITT, and it also interrupts the circuit shunting the 811 code contact of code transmitter IICT so that as a result of the release of the contact previously traced circuit for supplying current of the 80 code frequency to the track transformer IUTT is complete and controls the supply of current to that track transformer.

It will be seen that the release of the contacts of relay I'IBSB not only establishes a circuit through which current may be supplied from terminal BX of the source of signal control curcent to the track transformer HTT, but it also interrupts the circuit of the winding. of relay IIFSB so that the contacts of relay IIFSB become released. Accordingly contact I6 of relay I IFSB interrupts the steady energy or lockout circuit for section WT, and there is no possibility that steady energy will be supplied to the rails of section IIJT at this time. Instead, as pointed out above, energy of the 80 code frequency will be supplied to the track circuit. of section IIJT.

On release of the contacts of relay HBSB contact 66 interrupts the circuit for energizing the winding of relay III-I, and after a time interval determined by the release time of relay IIH, the contacts of this relay become released. Because of the, slow releasing characteristics of relay IIH, the contacts of this relay remain picked up until after the contacts of relay IIFSB become released, and accordingly on release of contact 60 of relay III-I no circuit is established to energize the winding of relay relay 1 IFSB will have released before contact 66 becomes released.

On release of the contacts of relay l II-I contact 95 interrupts the circuits of the proceed lamrps G and Y of signal HS and engages back contact 91 to complete the circuit for energizing the stop lamp R of signal IIS.

In addition, on the release of the contacts of relay IIFSB contact 39 engages contact 45 to complete the circuit for energizing the winding of relay I IFSA and the contacts of that relay become picked up, but since contact I6 of the track relay IITR remains picked up, picking up of contact 360i relay IIFSA is without effect.

From;- the foregoing, it will be seen that if an insulated joint separating two track sections becomes defective so that the energy supplied to the rear section feeds over the defective joint and energizes thetrack relay of the forward section, the lookout circuit will be established to supply uncoded energy to the rear section on the third operation of the contacts of the track relay of the forward section; and that thereafter the contacts of the track relay of the forward section are maintained picked up by the steady energy feeding over the defective joint. I

The contacts of the track relay of the forward section will be held picked up even after the train has vacated the track section and coded energy is supplied to the track circuit of such forward section, since the steady energy from the rear section feeding over the defective insulated joint will prevent release of the contacts of the track relay of the forward section during the off intervals of the coded energy supplied to the forward section. Accordingly once the lockout circuit for supplying steady energy to the track circuit in the rear of a defective insulated joint is established, the circuit will be maintained after the track stretch becomes unoccupied.

In addition, as pointed out above, it will be seen that on the supply of steady energy to the track circuit of a track section as a result of the operation of the lockout circuit associated with the track relay of the adjacent track sectionin advance of the section to which the steady energy is supplied, the track relay of such sec- IIFSB since contact 59 of be established and coded energy will be supplied to the track circuit in the section in the rear of 1 that track relay.

The operation of the equipment shown in Fig. l in the event an insulated joint becomes defective as a result of passage of a train having been described, the operation of the equipment in the event an insulated joint becomes defective when the track stretch is unoccupied will now be considered.

For purposes of illustration it will be assumed that one of the insulated joints separating the track sections HT and IZT becomes defective at a time when neither of these sections, nor the section in advance of section MT, is occupied.

' As the section in advance of section I2T is assumedto be unoccupied, coded energy of the I89.

code frequency is supplied to the track rails of track section IZT, while the apparatus associated with the track relay IZTR operates in the manner described above to supply energy of the I code frequency to the rails of section HT.

At this time as the track relay IZTR is responsive to energy of the H30 code, the relays IZFSB, IZBSB, IZH and IZJ are energized and their contacts are picked up.

As long as the insulated joints separating the sections HT and HT are intact, the track relays I IT and I2T will respond in the usual manner to the current of the I86 code frequency. However, when the insulated joint separating sections HT and breaks down to a substantially zero resistance, energy of the I89 code frequency supplied to the rails of the section I IT will feed over the defective joint and energize the winding of relay IZTR.

If at the time the joint breaks down, the impulses of coded energy supplied to section I IT are out of step with those supplied to the section lZT, then the impulses of current supplied to the section I IT, and feeding over the defective joint, will fill in the spaces between the impulses of energy supplied to section I2'I and the track relay IETR will be energized all or substantiallyall of the time, while its contacts will be maintained picked up all or a large portion of the total time.

If at the time the insulated joint breaks down the impulses of coded energy supplied to the section I IT are substantially in step with those supplied to the section lZT, the winding of track relay IZTR will be supplied with current of abnormally high value, and, as a result, the contacts of the track relay IZTR will occupy their picked up position for a much larger proportion of the total time than they occupy their released position. This characteristic is inherent in the single element track relay design and results from the fact that abnormally high values of relay energizing current pick up the relay contacts more quickly, and introduce a corresponding delay in the release of the contacts because of the higher intensity of the magnetic flux created as a result of energization of the relay winding. This flux must, of course, die down to a predetermined value before the contact carrying armature of the relay can be released under the biasing action of the usual spring or of gravity.

In consequence of the lengthened picked up 'periods of the contacts of track relay IZTR,

whether caused by an increase in the portion of the time during which the relay winding is energized or by an increase in the degree of energization of the 'relay'winding, the contact I6 of I2T becomes defective, assuming that it relay I2TR will not engage back contact I8,-'or willengage it for such short intervals that energization of the winding of relay I2BSB is reduced below the value effective to maintain the relay contacts pickedup.

On release ,of the contacts of relay IZBSB the circuits of the windings of relays I2FSB and IZH are interrupted, while the circuit connecting snubbingresistor 40 across the terminals of the Winding of relay IZFSB is also interrupted so that the contacts of relay IZFSB become released before the contacts of relay IZH become released.

As a result of the release of contacts of relays I2FSB and IZBSB, the circuit for supplying energy of the I80 code frequency to the rails of track section HT is interrupted, while the circuit for supplying energy of the 80 code frequency to section HT is established. The current of 8!! code frequency supplied to the rails of section HT will feed over the defective joint and will combine with the impulses of energy of I80 code frequency supplied to section I2T. The scrambled code resulting from a mixture of the impulses of the 80 and the I80 code frequency will cause the contacts of relay IZTR to remain picked up most of the time, thereby energizing relay IZFSA, but within a very short time interval the relationship of the two code impulses will be such that the contacts of relay IZTR will become released and will establish the circuit for energizing the winding of relay 'IZBSA. On subsequent picking-up of the contacts of relay IZTR energy is supplied to the winding of relay IZFSB.

- On picking up of the contacts-of relay I2FSB the lockout circuit for supplying steady energy to the rails of track section HT is established, and this steady energy feeding over the defective insulated joint will maintain the contacts of track relay I2TR setadily picked up, while the relay IZ'I'R will maintain the circuit of the winding of relay IZF'SB which in turn maintains the lock .out winding of relay I2FSB which in turn maintains the lockout circuit intact.

At this time both of the relays I 2H and I2J are deenergized and the signal I2S will be conditioned to display its stop indication, while signal I IS will also be conditioned to display its stop indication.

The equipment provided by this invention and shown in Fig. 1 of the drawings will also operate in a similar manner if the insulated joint separating two track sections only partially breaks down, that is, if the joint breaks down sufficiently to permit some current to feed over the joint, but retains sufiicient resistance to prevent the full value of the'signal control energy feeding over the joint.

Under such conditions if the code impulses of the sections HT and I2T are in step, the increase in the degree of energization of the Winding of relay IZTR. may not be suflicient to increase the duration of the picked up periods of the relay contacts, and thereby reduce the duration of the released periods of the relay contacts enough to cause the release of th contacts of relay I2BSB.

However, the coding devices I2CT and for the adjacent section in advance of section I2T are operated by induction motors and the speed of these motors will vary slightly so that the inphase relationship of the code impulses supplied by the two coding devices will not be continuous, and the code impulses, if in step at the time the joint becomes defective, will soon fall out of step. As the code impulses of sections I2T and I IT approach the condition in which the off period of one code is filled in by the on period of the other code, the contacts of the track-relay I'2TR wil1-'be picked up such a large proportion of the timethatthe contacts of relay I ZBSB will become released and establish ment of the lockout circuit will follow in the manner described above.

The system provided by this invention is arranged so that in the event :the lookout circuit, when once established, is improperly interrupted, or if feeding ofcurrent over the defective joint is .interrupted, the lockou circuit will be subsequently automatically reestablished.

For purposes of illustration it will be'assumed that one of theinsulatedjoints separating sections HT and IZTis defective,.and that the equipment associated wtih relay IZTR has operated to establish the lockout circuit to supply steady energy to the rails of section HT, and that this steady energy feeds over the defective joint and maintains the contacts of relayv IZTR constantly picked up. It will also be assumed that thetrack stretch is unoccupied so that energy of the ISO code frequency is supplied to the rails of section HT, and that under these conditions the feeding of energy from section IIT to section IZT over the defective joint is temporarily interrupted.

Since itis assumed that the: equipment associated with relay IZTR is conditioned to establish the lookout circuit, the relay IZFSB will be energized, while the other relays associated with relay lZTR. will be deenergiz ed.

When the supply of steady energy to the relay IZTR is interrupted, the contacts of the relay begin to follow'the I code which is supplied to this section at this time. period in the code the contacts of relay I2TR become released, and a circuit is established to energize the winding of relay I2BSB, this circuit including contacts 2I-24 of relay I2FSB. Accordingly the contacts of relay IZBSB become picked up so that on the next picked up period of the track relay contacts energy is supplied to the winding of relay IZH, while as a result of picking up of the contacts of relay I2BSB a stick circuit is established for supplying energy to the winding of relayIZFSB after picking up of the contacts of relay IZI-I.

On picking up of the contacts of relays IZBSB and IZI-I the lookout circuit is interrupted, while the circuit for supplying energy of the I80 code frequency to the rails of section IIT is established. On the supply of current of the I80 code frequency to the rails of section IIT the relay HTR, follows this code and the equipment associated with relay IITR operates in the manner described above so that relays IIBSB and l II-I become energized. In addition as track relays IZTR, and I ITR are responding to energy of the Ito code frequency the relays IZJ and IIJ are energized and the green lamps G of the signals I28 and IIS are illuminated. This condition will continue as long as the track stretch is unoccupied and energy does not feed over the defective joint.

When energy again feeds over the defective joint, the contacts of relay I ZTR will be held pickedup an abnormally large proportion of the time and (the contacts of relays IZFSB,

WBSB and. IEH will become released, as explained above, thereby interrupting the-supply of current of the I80c0de frequency to section i 9'1 and establishing a circuit to supply current of 8 code frequency thereto.

Subsequently relays I2FSA, IZBSA, and I2FSB will be energized successively, and on picking up On the first off of the'contacts of relay IZFSB the lockou j'cir'-, cuit for supplying steady energy to therailsof section I IT will be established; and steady energy will feed over the defective insulated joint and vw'll maintain the'contacts of track relay IZTR picked upso that relay IZFSB will be maintained energized to maintain the lockout circuit.

The equipment will operate in a similar manner if after the lookout circuit is; established tive insulated joint to relay IETR sothat relay IZTR now follows the I 8i? code which is supplied to the rails of section I2T. v

When track relay IZTRfollows code, relays IZBSB and IZI-I become'energized, as explained above, and the lockou or steadyenergy supply circuit is interrupted, while energy of the 188 code frequency is supplied'to section IIT:

The impulses of energy of- I89 code 'fre quency supplied to the rails of-section =I IT will feed over the defective insulated joint and energize relay IZTR. .As explained above, .the ,contacts of relay I2TR'will be picked'up an abnormal portion .ofthe total time becauseof the increase in the energizedtime of relay I2TR or because of the increase in-the degreeof energi-v zation of the relay winding. As a result of this condition, the contacts of relay IZBSB will be! come released, thereby interrupting the circuits of the windings of relays IZFSBand IZI-I, while on the release of the contacts. of relaylZESB the circuit for energizing the winding of relay IZFSA is established and. this relay becomes energized on a picked up period of the track relay contacts. At this time as wire'85 is, assumed to be. disconnected from contact 84 the circuit for sup-, plying energy of theSIl code frequency to section I IT is not complete even though contact I9 of relay I2 BSB and contact 16 of-relay IZESBjare re v leased. As energy of the '8ll"'code frequency is r not supplied to section II T, therewill be no"'feed-' ing of these 'impulses'totrack relay I ZTRand the relay I2'IR will continue to' follow energy-of 1'80 code frequency supplied to the section I2T On a. subsequent released periodiofthe'track' relay contacts relay MESA-becomes energized,

while on a subsequent :picked up period of the.

trackrelay contacts relay- IZFSB- becomes picked up, and on picking upof the contacts: of this relay a stick circuitr is establishedto supply .en-.

ergy to the winding of relay I2FSB after the contacts of relay IZBSA become released.. 1

On picking up of the contacts of relay I2FSl3 contact It establishes the lockou circuit and steady energy will be supplied to therails of sec-. tion I IT if wire isr-again connected tocontact 84. If wire 85 is not. connected to contact, then on picking .up.ofcontact 'II-B of relay I2FSB no energy is supplied to section I.IT, and', hence energy does not feed over the defective joint to I 2FSB energy will be supplied to the-winding of relay I ZBSB. On picking up of the contacts of relay I2BSB a circuit is established to supply current to the Winding of relay I2H on the next picked up period of the track relay contacts, while on picking up of the contacts of relays IZBSB and I2H the circuit for supplying current of the I80 'code frequency to section HT is complete and current of this code frequency will be supplied to section HT.

On the supply of energy of the I80 code frequency to the rails of section IIT the impulses of current feed over the defective joint and energize relay [2TH so that the cycle of operations outlined above will be repeated.

As a result of this mode of operation of the equipment, impulses of current of the I 80 code frequency will be supplied to section I IT, and the signal IIS may be conditioned to periodically display its yellow or green aspect. This is proper as the track sections in advance of signal I IS are unoccupied.

' If wire 85 subsequently becomes connected to contact 84, then at the time in the cycle of operation of the relays associated with relay IETR at which the contacts of relay IZFSB become picked up the lookout circuit will be established and steady energy will be supplied to the rails of section HT, and this. energy feeding over the defective joint will maintain the contacts of relay I2TR picked up and thus maintain the lookout circuit.

A similar method of operation will result if the supply of steady energy to section II T is in-. terrupted because of breakage, disconnection or shorting of wire 75 leading to the primary winding 14 of track transformer I ITT at a time when the lockou circuit should be established. Under such conditions no energy is supplied to section HT and signal IIS displays a stop indication, while relay I2TR will respond to energy of the I80 code frequency supplied to section I2T so that signal I2S will display its green aspect and the circuit forsupplying energy of I80 code frequency to the track transformer I ITT will be established except for the wire I5.

As long as the circuit of wire I is impaired,

the condition outlined above will be continued, but as soon as the circuit of wire I5 is restored, energy supplied to sction IIT will feed over the defective joint and will energize relay I2TR with the result that the equipment associated with relay I2TR will operate in the manner-described above to establish the lookout circuit to supply steady energy to section II T. Since the circuit of wire'15 is now intact, this steady energy will reach the rails of section IIT'and will feed over the defective joint and will maintain relay IZTR constantly energized so the lookout circuit will be maintained.

' From the foregoing it will be seen that the system provided by this invention is arranged so that the lockout circuit is self-restoring in the event that after it is established it is improperly interrupted for any reason.

The system provided by this invention is adapted for use in track stretches which include intersections with highways as this system makes it possible, to employ steady energy to discontinue operation of highway crossing signals without interfering with the operation of the signals controlling movement of trafiic in the track stretch with'which the signal system is associated.

Construction of system shown in Fig. 2 0 the drawings Referring to Fig. 2 of the drawings, there is shown therein a stretch of railway track over which traific normally moves in the direction indicated by the arrow, the track stretch including an intersection'with a highway, the intersection being protected by crossing signals X and the railroad track stretch being equipped with signaling apparatus embodying this invention.

For purposes of illustration it will be assumed that the highway crossing is located in advance of signal MS, and that the track section in advance of the signal MS is divided into two sections identified as AMT and EMT, the insulated joints 3 separating these sections being located adjacent the highway crossing. At the cut section separating the sections AMT and EMT there is located cut section apparatus for at times supplying coded energy to the track rails of section BI4T, and at other times supplying steady energy to the rails of section BI4T.

The track stretch shown in Fig. 2 of the draw ings may be assumed to be a continuation of that shown in Fig. 1 of the drawings, and impedance bonds 4 are provided to transmit propulsion current around the insulated joints which separate the various track sections, while the other parts of the system shown in Fig. 2 are the same as the corresponding portions of the system shown in Fig. 1 except ashereinafter specially pointed out in detail.

The cut section apparatus includes a code following track relay AMTR having its winding connected to the track rails of the track section Al 4T through a resonant unit AI 4RU. The relay AMTR has associated therewith code detecting relays AIAFSA and AIABSA, while contact I20 of the relay AMTR controls the circuit for energizing the relays AMFSA and AI IBSA.

Contact I20 is constantly connected to terminal B of a local source of direct current, such as a battery, not shown, while contact I20 when picked up engages contact. I22which is connected by wire I23 to one terminal of the winding of relay AI 4FSA, the other terminal of which is connected to terminal C of the source of current. A snubbing resistor I25 is constantly connected across the terminals of the winding of relay AMFSA to render the relay contacts slow in releasing.

Contact I20 of relay AI ITR, when released, engages contact IZ'I which is connected by wire I28 to a contact I29 which is engaged by movable contact I30 of relay AMFSA when contact I30 is picked up. Contact I30 is connected by wire I3I to one terminal of the winding of relay AMBSA, the other terminal of which is connected to terminal C of the source of current. A snubbing resistor I33 has one of its terminals connected to one terminal of the winding of relay AMBSA, while a branch of wire I28 is connected to the other terminal of the resistor. Accordingly, when contact I30 is picked up, a circuit is established from wire I28 to the winding of relay AI IBSA, while, in addition, the snubbing resistor 133 is connected across the winding of relay AMBS'A. I

The relay AMBSA has a contact I35 which is connected to terminal BX of the source of 100 cycle signal control current, while contact I35 when released engages a contact I 36 which is connected by wire 15a to one terminal of the primary winding I4 of track transformer BI4'IT,

the other terminal of which is connecteddso ter= minal CX of the source of signal control current.

Contact I35 when picked up engages a contact I31 which is connected by wire I38 to contact I39, while the track relay AMTR. has a contact I40 to which is connected a-branch of wire 15a and which when released engages .contact I39.

In addition, the relays AI IFSA and AI4FSB have contacts I43 and I44, respectively, which control the circuit from terminal B of the local source of direct current to one terminal of the winding MS of interlocking'relay XR, the other terminal of which is connected to terminal C of thelocal source of direct current.

The interlocking relay XR controls the crossing signals X for protecting the highway intersection. The details of construction of theinterlocking relay XR are not a part of this invention and any suitable relay of standard construction may be employed.

The secondary winding of track transformer BMTT is connected .to the track railsof track section BI 4T in the usual manner;

The equipment associated with track relay BI 4TB, except for the additions necessary to control the circuit of the winding I48 of interlocking relay XR, is the same as that employed in the system shown in Fig. 1, and the same reference characters are employed to identify the apparatus of Fig. 2 as are employed in Fig. l, except'fo-r a change in the designation of the relays which have been given a prefix corresponding to'that of the trackrelay with which they. are associated.

The additions necessary to control the winding I48 of interlocking relay XR comprises a contact I50 for relay Bi IFSA,.a contact I5l for relay BMBSA, and a contact I52 for relay BMI-I. Each of these contacts has connected thereto-a branch of wire I53 leading to one terminal of .the winding I48 of relay XR, the other terminal of which is connected to terminal C of asource of direct current associated with .track relay BI ITR.

Each of the contacts I50, I5I and I52, when picked up, engages a stationary contact to which is connected a wire leading from the terminal B of the local source of directcurrentso that the winding MB of relay XR is energized whenever anyone of the contacts I50, I'5I, and I52 is picked up, and is deenergized when andonly when all three of these contacts are released.

Operation of equipment shown in Fig. 2 of the drawings The construction of the equipment shown in Fig. 2 having been described, its operation will now be explained. For purposes of illustration it will be assumed that the sections BI AT and AI 4T are unoccupied, and that the section inadvance of section AMT is also unoccupied. Accordingly current of the I code frequency will be supplied to the rails of section AI IT and the contacts of the relay AI 4TB. will be picked up and released in accordance with this code frequency. During the picked upperiods of thetrack relay contacts, contact I20 engages contact I22 to energize the winding of relay AIAFSA, while during the released periods of the track-relay contacts, contact I20 engages contact I21 'to supply current to the winding of relay AI IBSA. It willbe observed that the circuit of the winding :of relay AI lBSA is complete as long'as contact I30 of relay AI lFSA is picked up. As long as the con"- tacts of track relay AI' ITR, continue 'to follow code, therefore, the windings of relays AMF'SA and AMBSA will be alternately energized, and

thenontacts of'nthes'etrelays'are'slow enough in releasing to remain picked up between the impulses of current to theirwindings.

Accordingly contact I35 of relay AI lBSA is picked upto thereby interrupt the circuit for supplyingsteady energy to track section BI IT, while during the released periods of-contact I 40 of track relay AI 4TB, a circuit is established to supply energy to the rails of section BI IT. This circuit is interrupted during the picked periods of relay contact Hi5 so that as long as coded energy is supplied to the track relay AI ITR, this relay operates to supply current of the same code frequency tothe rails of section BItT.

It willbe apparent that if the section in advance of section AMT were occupied and current ofthe code frequency were supplied to the rails of section AMT, the contacts of track relay AI iTR would followthis code and would supply coded energy of the same code frequency to the rails of track section BMT.

:Asrelays AI IFSA and'A'I iBSA are both energized their contacts I43 and I4 1 are picked up and establish the circuit for energizing the winding I46 of interlocking relay R,

As a result of the supply of current of the I80 code frequency, to therails of section EMT, the contacts of code fo-llo-wingtrack relay BMTR are picked up and released in accordance with this code frequency. The equipment associated with track relay BI 4TH will operate in the manner described-in detail in connection with the system shown in Fig. 1, and as long as the relay BMTR continues to follow code of the I803 code frequency, the relays BI AFSB, BMBS-B, BI dJ and BIAH .will be energized and their contacts will be picked up. Accordingly the circuit for supplying current'of the I80 code frequency to the section in the rear of section BMT is complete, while as the relays BI IJ and B I 4H are both energized, the contacts of theserelays establish the circuit to illu minate the green lamp G of'signal MS.

In addition, at this. time contact I52 of relay B I 4H is picked up and establishes connection from terminal B of the source of direct current to wire I53.-with.the result that winding I68 of interlocking relay XR is energized. As both windings of theinterlocking'relay are energized, this relay operatesin-the customary manner to maintain the crossing signals X inoperative.

Operation of equipment shown in Fig. 2 on passage 0]" w trainin normal direction of tm fic If a train traveling from left to right enters track section BMT, the wheels and axles of the leading vehicle of the train will shunt the track relay BI 4TH, and the contacts of this relay will become released. 0n release of the contacts of relay BMTR contact I6 no longer engages its front point of contact stand accordingly the contacts of relay BMFSB become released, and on the release of thesecontacts the circuits of the windingsof relays BMBSB and BMI-I. are interrupted and those relays become deenergized and their contacts become released. 1 1

In addition, on shunting of the relay BI lTR. relay BI IJ becomes deenergized and its contact becomes released.

On release of contact of relay BMI-I the circuit of the green lamp G is interrupted and the circuit for the red lamp R. of signal MS is established,

On release of contact I52 of relay BMH the circuit for energizing the winding I48 of interlocking relay XR-isinterrupted; and the armature, not

shown, controlled by this relay winding becomes released and initiates operation of the crossing signals X to warn users of the highway of the approach of a train.

As long as any part of the train remains in track section BI 4T, the track relay BI4TR remains shunted and the other relays associated with this track relay remain deenergized.

When the forward portion of the train enters track section AMT, it shunts the track relay AI4'I'R, and the contact I20 of this relay no longer intermittently engages its front point of contact I22 with the result that the winding of relay AI4FSA becomes deenergized and its contact I30 opens the circuit for energizing the winding of relay AI4BSA, and, in addition, opens the circuit by means of which snubbing resistor I33 is connected across the terminals of the relay winding with the result that the contacts of relay AI 4BSA thereafter quickly release.

As a result of release of contact I35 at this time, steady energy is supplied to the track rails of section BMT, while as a result of the release of contacts I43 and I44 of relays AI4FSA and AI4BSA, the circuit of the winding I46 of relay XR is interrupted. However, because of the internal construction of the interlocking relay XR, on deenergization of winding I46 subsequent to deenergization of winding I48, the armature, not shown, controlled by winding I46 is not permitted to move to its release position, but at this time operation of the crossing signals X is continued by the circuit controlled by the armature associated with winding I48.

As long as any portion of the train remains in track section BI4'I, the track relay of that track section remains shunted, but when the train has advanced far enough so that the rear of the train passes out of section BI 4T, the steady energy supplied over the circuit established by contact I35 of relay AMBSA to the rails of track section BI4T will be fed to the winding of track relay BI 4'I'R to cause the contacts of this relay to become picked up. On picking up of contact I6 of relay BI4TR a circuit is established to energize the winding of relay BI4FSA, this circuit being traced from terminal B of the source of current through wire I1, contacts I636 of relay BI4TR, wire 38, contacts 39-45 of relay BI4FSB, wire 46, winding of relay BMFSA and snubbing resistor 41 in parallel to terminal C of the source of direct current. As a result of energization of the winding of relay BI 4FSA, the contacts of this relay become picked up and contact I50 establishes connection from terminal B of the source of direct current to Wire I53 leading to the winding I48 of interlocking relay XR,

As a result of energization of the winding I48 of interlocking relay XR, the armature controlled by this winding becomes picked up to interrupt further operation of the crossing signals X. On picking up of the armature controlled by the winding I48 the armature controlled by winding I46 continues to be prevented from releasing with the result "that operation of the crossing signals X is discontinued.

As long as steady energy continues to be supplied to the track section BI4T, the contacts of relay BMTR. are maintained picked up and relay BI4FSA is maintained energized, while energy of the code frequency is supplied to the track section in the rear of section BI4T since relays BMFSB and BI4BSB are both deenergized.

On the supply of steady energy to section B-I4'I and pi'cking'up of contact of relay BI4TR, the relays BI4J and BI4I-I both remain released and contact 95 continues to establish the circuit for illuminating the red lamp R so that the signal I4S continues to display its stop indication.

When the train advances into the track section in advance of section AI4T, the track relay for that section becomes released and the apparatus controlled by that track relay is thereby conditioned to supply current of the 86 code frequency to the rails of section AI4T. As long as any portion of the train remains in section AI4T, the track relay of section AMT remains released, but when the rear of the train vacates the section AI4T, the energy r'of 86 code frequency feeds to the track relay AI4TR. As a result of operation of the contacts of the track relay AI4TR in response to current of the 80 code frequency, the relays AI4FSA and AI4BSA are energized, while contact I46 of the track relay effects the supply of current of the 80 code frequency to the track rails of section BMT.

In addition, on energization of the windings of relays AI4FSA and AI4BSA, contacts I43 and I44of those relays become picked up and complete the circuit for energizing winding I46 of interlocking relay XR. On energization of winding I46 the armature controlled by this winding becomes picked up and is removed from control by the armature associated with winding I48 of the relay XR.

On the supply of current of 86 code frequency to the rails of section BI IT following the period in which they have been supplied with steady energy, the contacts of the track relay BI4TR become released during the first oiT period in the code and eifect energization of the winding of BI4BSA, while on the next on period of the code the contacts of the track relay BI4TR are picked up and energy is supplied to the winding of relay BMFSB.

On picking up of the contacts of relay BI4BSA contact I5I establishes a circuit from terminal B of the source of current to wire I53 so that on release of contact I50 of relay BMFSA the winding I48 of interlocking relay XR. will not be deenergized.

On the neXt movement of the contacts of track relay BI4TR to their released positions following picking up of the contacts of relay BMFSB a circuit is established to energize the winding of relay BI4BSB, while on picking up of the contacts of relay BI4BSB a circuit is established to energize the winding of relay BI lI-I. On picking up of the contacts of relay BI 4H contact I52 establishes connection from terminal B of the source of direct current to wire I53 to maintain the winding I48 of interlocking relay XR energized. The circuit for energizing the winding of relay BI 4BSA was interrupted on picking up of the contacts of relay BI4FSB, but the release time of the relay BI4BSA and the pick-up time of the relays BI4BSB and BI4H are proportioned so that the contacts of relay BI4BSA will remain picked up, and contact I5I will maintain the circuit for energizing the winding I48 of interlocking relay XR, until after contact I52 of relay BI4I-I becomes picked up to establish the circuit of the winding I48 and prevent deenergization of this winding on subsequent release of the contact I5I of relay BI4BSA. Accordingly thewinding I48 of the interlocking relay will be maintained energized throughout the cycle of operation/of the relays associated withtrack relay BI4TR and the crossingsi'gnals X will be maintained inoperative.

On picking up of. the contacts of relayBI4FSB at a time when the contacts. of relay BI4BSB are released the steady energy supply circuit or lockout circuit is established to supply steady energy to the section in the rear of section BI4T,

while on picking up of contact I9 of relay BI4BSB the lockou circuit is interrupted and the circuit for supplying energy of the I code frequency tothe section in the rear of section BI4T is established when contactof relay BIN-Ibecomes picked up.

Inaddition, on pickin up-of the contacts of relay Bi II-I contactinterrupts the circuit of the red lamp R and completes the circuit of the yellow lamp Y of the signal I4S.

The other operations of the relays BI4FSB, BI4BSB, and B'I4H are the same asdescribed in detail in connection with Fig. 1 and will not be repeated here.

When the train has advanced far enough in the track stretch to clear the section in advance of section AMT so that current of the I80 code frequency is supplied to section AI 4T, the track relay AMTR repeats the supply of current of I80 code frequency to section BI4T, while on the supply of current of this code frequency to track relay BI4TR the resonant unit BMR'UA supplies sufficient energy torelay BI IJ to effect picking up of the contacts of this relay to thereby'extinguish the yellow lamp Y and light the green lamp G of signal I4S.

In-the event an insulated joint separating section BMT and the adjacent section in the rear becomes defective so that current supplied to the rails of such section in therear feeds over the defective joint and energizes the track relay BI ITR, the equipment associated with the relay BI 4'IR'will operate in the manner described in detail in connection with the system shown in Fig. l of the drawings to establish the lockou circuit to supply steady energy to the 1'ear'sec-' tion, and to maintain the contacts of the track relay BI I'IB picked up, whilethe signal S will be conditioned to display its stop indication.

When the lockout circuit is established, relay BI4FSB is energized and its contacts are picked up, thereby interrupting the circuits of the windings of relays BI4FSA and BI4BSA so that the contacts I50 and I5I of those relays are released. In addition, at this time relay BItI-I is deenergized and its contact I52 is released. As the contacts I50, I5I, and I52 are all released, no circuit is established to energize the winding I48 of interlocking relay XR, and the armature controlled by the winding I48 is released and effects operation of the crossing signals X'even though a train is not approaching the highway intersection. This, however, is a safe condition.

Operation of equipment shown in Fig. 2 on passage of a train in the reverse direction of traffic The operation of the equipment shown in Fig. 2 during passage of a train in the normal direction having been described, its operation on passage of a train in the reverse direction of traffic will now be considered. It will be assumed that the track stretch is unoccupied so that the track relay BI4TR is supplied with energy of the code frequency, while the signal MS is displaying its clear indication.

When the train moving from right to left enters the section in advance of section Al 4T, the equipment associated 'with thatsection is conditioned to interrupt the supply of current of the 180 code frequency, and to supplycurrent of the 80 code frequency to the rails of: section AI 4T, while track relay AIlTR' supplies energy of this lower code frequency tothe rails of section BI4T. On this change in the supply of current to section BI4T to the lower code frequency the relayv BI4J is de-.

energized andthe signal I IS is conditioned to display its caution indication.

1.At this time as. track relay AI4TR is following code the relays AI 4FSA and AI4BSA are both energized, while their contacts I43 and I44 are maintained picked up and establish the circuit of the winding I46 of relay XR. In addition,.at' this time contact I52 of relay BI4I-I is pickedup and the winding I 48Iof relay XR is also energized. As both winding-s of the interlocking relay XR are energized, the crossing signals'X-are maintained inactive.

As the trainproceeds to the left and enters sectionAI-AT, it shunts the track relay. AI4TR and the relay contacts thereafter. remain in theirreleased position. Asa result, the winding of relay- AI-4FSAis deenergized and the contacts of this relay become released. On release of contact I43 of relay AMFSA the circuit of the winding I46 of interlocking relay XR'is interrupted, and-the armature controlled by winding I46 becomes released and initiates operation of the crossing signals X to warn .users of thehighway of the approach of a train.

On release of contact. I30 of relay AI4FSA the circuit of the winding of relay AI4BS'A is interrupted, while, in addition, the circuit by means of which snubbing resistor I33 is connected across the winding of the relay AIIBSA is interrupted so that the contacts of. relay AI4BSA' quickly becomereleased. On release of contact I35 of relay AMBSA the steady energy supply circuit is established to supply energy to the primary winding -14 of the track transformer BI4TT- with the BE lFSB, and the contacts of relay BMFSB thereupon become released. In addition, the contact 65 of relay BIABSB interrupts the energizing circuit for the winding of relay BI4I-I so that the winding of relay BI4I-I isdeenergized and the relay contacts becomereleased.

On release of the contacts of relay BI4FSB contact-39 engages contact to establish a circuit for'energizing the winding of relay BI4FSA with current supplied over contacts I636 of the track relay BMTR. Accordingly the winding of relayBItF'SA will be energized. and contact I50 of this relay willbe picked up to establish the circuit to maintain winding I48 of interlocking relay XE energized following release of'contact I52 of relay BMI-l. As pointedout above, contact I50 of relay BMFSA will become picked up before contact I52 becomes released, and hence Winding M8 will be continuously energized.

Onrelease of contact 95 of relayBI II-I the circuitfor energizingthe yellow lamp Y of signal I' ISis-interruptedand lamp'R of the signal is 75 illuminated to indicate that the section in ad- Vance of the signal IRS is occupied.

. At this time as the relays BI 4FSB and BI IBSB are both deenergized, the contacts I6 and I9 of these relays are released and the circuit for supplying current of the 80 code frequency to the primary winding M of track transformer I3TT is complete, while the supply of current of 180 code frequency to the transformer I3TT is cut off.

As the train continues its movement to the left and enters track section BMT, it shunts the track relay BI iTR and the contacts of this relay become released and remain in their released positions. On releaseof contact I6 of relay BI ITR, the. circuit for energizing the winding of relay BMFSA is interrupted, and, after a brief time interval, the contacts of this relay become released, and on release of contact I50 of relay BMFSA the circuit of the winding I48 of interlocking relay XR is interrupted, and the armature controlled by this relay winding moves toward its released position. This armature, however, is prevented from moving all of the way to its released position because of, the prior release of the armature controlled by winding M6. At this time operation of the highway crossing signals X is continued by means controlled by the armature associated with Winding I46 of the interlocking relay XR.

, As the train continues through the track stretch far enough so that the rear of the train is no longer present in track section AMT, the track relay AM'I'R, will respond to coded energy supplied to the rails of section AI 4T by the means associated with the adjacent section in advance.

As a result of code following operation of the contacts of relay AI lTR, the relays AI IFSA and AMBSA are energized and their contacts I43 and I44 become picked up and establish the circuit of the winding I46 of interlocking relay As a result, the armature controlled by winding I46 becomes picked up to discontinue operation of the highway crossing signals X and to continue to prevent releasing movement of the armature controlled by winding I48.

On picking up of contact I35 of relay A|4BSA a circuit is established to supply energy to the primary winding N of track transformer BMTT during the released periods of contact I40 of the track relay AMTR. At this time, therefore, coded energy of the same code frequency as is supplied to track relay AMTR will be supplied to the rails of section BIAT, but as long as any portion of the train remains in section BI4T, the track relay BI iTR will be shunted.

When the train has advanced farther in the track stretch so that the rear of the train clears the left-hand end of section BI lT, track relay BMTR responds to the coded energy supplied to the rails of this section, and on the first picked up period of the track relay contacts energy is supplied to the winding of relay BMFSA, and on energization of this winding contact I50 is picked up and establishes the circuit for energizing the winding I48 of relay XR and the armature controlled by winding I48 is then moved to its picked up position.

The equipment associated with track relay BIATR will thereafter operate in the manner described in detail above, and its operation will not be repeated here.

From the foregoing it will be seen that the system provided by this invention provides an improved lockout circuit which is non-cascading in operation, that is, on failure of an insulated joint separating two sections steady energy is supplied to the rearward -one of the sec tions, but the supply of steady energy is not repeated beyond such rearward section.

The non-cascading action of the system provided by this invention results from the fact that the lookout or steady energy circuit is not established .by the first picked up period of the track relay contacts following a period during which they have been released or have been following coded energy for a substantial time. Instead the lockout or steady energy supply circuit is established on the second picked up period of the track relay contacts so that the lookout circuit is established only if after the track relay contacts have been released for a period, they follow code for a brief time interval. Similarly, if after a track relay has been following coded energy for a time interval steady energy is supplied to the track relay, the lockou or steady energy supply circuit will not be established.

This method of operation insures that the lockout circuit will not be established if steady or non-coded energy is supplied to a track relay by means other than the lookout circuit which is controlled by the track relay, but that the lockout circuit will be established and will be maintained if steady energy supplied over the lookout circuit feeds to the track relay controlling the lockout circuit.

Since the improved system provided by this invention is inherently non-cascading in operation, it is unnecessary to provide cut section facilities to break up cascading action, while steady energy may be employed where desired, as for example for discontinuing operation of highway crossing signals, without interfering with operation of the railway traffic governing means.

It will be seen also that the system provided by this invention is arranged so that the lockout circuit is self-restoring, that is, if for any reason the lookout circuit should be interrupted after it has once been established the circuit will automatically restore itself.

Although I have herein shown and described one illustrative embodiment of my invention, together with one modification thereof, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a coded railway signaling system, in combination, a stretch of railway track having a pair of track rails divided by insulated joints into a plurality of successive track sections and including adjoining forward and rear track sections, means for supplying coded or uncoded energy to the rails of the forward section, a code following track relay for the forward section operated by energy received from the rails of such forward section, means operative on the release of the contacts of said track relay to establish a coded energy supply circuit to supply coded energy to the rails of said rear section, means governed by code following operation of said track relay contacts for establishing a steady energy supply circuit for supplying uncoded energy to the rails of said rear section, said means being operable to establish said steady energy supply circuit only after the track relay contacts have moved between their released and picked up positions a plurality of times, and

into a plurality of successive track sectionssand includingadjoining forward and rear track;sections, means for supplying coded or uncoded energy to the rails of the forward section, a code following track relay for the forward section operated by energy received from the rails of such forward section, means operative on the release of the contacts ofsaid track relay to establish a coded energy supplycircuit to supply coded energy to the rails of said rear section, means governedby code following operation of said track relay contacts for establishing a steady energy supply circuit for supplying uncoded energy to the rails of said rear section, said means being operable to establish said steady energy supply circuit only after thetrack relay contacts have moved betweenitheir released and picked up positionsa plurality of times, means also governed by code following operation of the track relay contacts for interrupting said steady energy supply circuit, said means being operable to interrupt said steady energy supply circuit only after a larger number of operations of the contacts of the code following relay than are required to establish said steady energy supply circuit, and trafiic controlling means governing movement of trains in said rear section, said means being responsive to energy supplied to the rails of said rear section and being selectively responsive to coded or steady energy.

3. In a coded railway signaling system, in com bination, a stretch of railway track having a pair of track rails divided by insulated joints into; a plurality of successive track sections, each of said sections having a code following track relay operated by energy receivedfrom the rails of such section, each of said track relays having associated therewith a steady energy supply circuit through which steady energy may be, supplied to the rails of the adjacent section in the rear'and a coded energy supply circuit through which coded energy may be supplied to the rails of the adjacent section in the rear, each section having means governed by the track relay for such section and controlling the associated steady energy supply circuit, each of said means being operative when the contacts of the'track relay are released for a predetermined time interval to interrupt the steady energy supply circuit, each of said means beingoperative on initiation of operation of the contacts of the track-relay to establish said steady energy supply circuit when and only'when the: trackrelay contacts have been moved between their two positions at least a predetermined number of times subsequent to the first movement of the said contacts from their released'position totheir picked up position, each of said means'being operative to interrupt the steady energy supply circuit on a movement of the track relay contacts between their picked up and released position subsequent to establishment of said steady energy supply circuit. l I v n j 4. In a. coded railway signaIin'g syStem, in combination,a-stretch of railway track having a pair of track rails divided by insulated joints into a plurality of successive track sections, each of said sections having a code following track relay energized by current supplied from the rails of such section, each of said track relays havingcontacts which occupy a released position when the relay is not energized and which occupy a picked up position when the relay is energized, each-of said track relays having associated therewith a steadyenergy supply circuit through which steady energy'may be supplied to the track rails of the adjacent section in the rear and a coded energy supply circuit through which coded energy may be supplied to the track rails of the adjacent section in the rear, each section having means governedby the track relay of such section and controlling the associated steady energy supply circuit, each of said means being operativew when the track relay contacts occupy their released position for a predetermined time interval to interrupt the steady energy supply circuit, each of said means being operative on initiation of code following operation of the contacts of thetrack relay to establish said steady energy supply circuit only as a result of a movement of said track relay contacts between their two positions at least once subsequent to the first movement of the contacts from their released to their picked up position after being in either of their positions for a time interval, each of said means being operative'to interrupt the steady energy supply'circuit on a movement of the track relay contacts between their two positions subsequent to establishment of said steady energy supply circuit.

5. In a coded railway signaling system, in combination, a stretch of railway track having a pair of track rails divided by insulated joints into a forward and a rear section, means for supplying steady or coded energy to the track rails of the forward section, a code following track relay receiving energy from the rails of the forward section, said track relay having contacts which occupy a released position when the relay isnot energized and which are moved to a picked up position when the relay is energized, a coded energy supply circuit through which coded energy plied to the track rails of said rear section, and means governed by said track relay for control-' ling said steady energy supply circuit, said means being operable to establish said steady energy supply circuit when and only Whenthe contacts of the track relay move between their two positions subsequent to initial movement of the track relay contacts to their picked up position after being in their released position for a period, whereby said steady energy supply circuit will not be established on the supply of steady energy to said-track relay at, a time when the relay contacts have been released for a period but will be establishedas a result of the supply of coded energy to the track relay at such times, said means also being operative to interrupt said steady energy supply circuit on a movement of tinues to respond to ooded' energy after establish ment of said steady energy supply circuit but will be maintained if energy supplied over said steady energy supply circuit on establishment thereof feeds past an insulated joint and maintains said track relay energized.

6. In a coded railway signaling system, in combination, a stretch of railway track having a pair of track rails divided by insulated joints into a forward and a rear section, means for supplying steady or coded energy to the track rails of the forward section, a code following track relay receiving energy from the rails of said forward section, said track relay having contacts which occupy a released position when the relay is not energized and which are moved to a picked up position when the relay is energized, a coded energy supply circuit through which coded energy may be suplied to the track rails of said rear section, said coded energy supply circuit being complete when the contacts of said trackrelay remain in their released position for a predetermined time interval, a steadyenergy supply circuit through which steady energy may be supplied .to the track rails of said rear section, and means governed by said track relay and controlling said steady energy supply circuit, said means being operable to establish said steady energy supply circuit on the second movement of the track relay contacts from their released to their picked up position after being in their released position for a period, whereby said steady energy supply circuit will not be established on the supply of steady energy to the track relay at a time when the relay contacts have been released for a period but will be established as a result of the supply of coded energy to the track relay at such time, said means being also operative to interrupt said steady energy supply circuit on a movement of the track relay contacts subsequent to that which effects establishment of said steady energy supply circuit.

'7. In a coded railway signaling system, in combination, a stretch of railway track having a pair of track rails divided by insulated joints into a forward and a rear section, means for supplying steady or coded energy to the track rails of the forward section, a code following track relay receiving energy from the rails of said forward section, said track relay having contacts which occupy a released position when the relay is not energized and which are moved to a picked up position when the relay is energized, a coded energy supply circuit through which coded energy may be supplied to the track rails of said rear section, said coded energy supply circuit being complete when the contacts of said track relay remain in their released position for a predetermined time interval, a steady energy supp-1y circuit through which steady energy may be supplied to the track rails of said rear section, and means governed by said'track relay and controlling said steady energy supply circuit, said means being operable to establish said steady energy supply circuit on the second movement of the track relay contacts from their released to their picked up position after being in their released position for a period, whereby said steady energy supply circuit will not be established on the supply of steady energy to the track relay at a time when the relay contacts have been released for a period but will be established as a result of the supply of coded energy to the track relay at such time, said means being also operative to interrupt said steady energy supply circuit on. the next movement of the track relay contacts to their released position after establishment of said steady energy supply circuit.

8. In a coded railway signaling system, in combination, a stretch of railway track having a pair of track rails divided by insulated joints into a forward and a rear section, means for supplying steady or coded energy to the track rails of the forward section, a code following track relay receiving energy from the rails of said forward section, said track relay having contacts which occupy a released position when the relay is not energized and which are moved to a picked up position when the relay is energized, a coded energy supply circuit through which coded energy may be supplied to the track rails of said rear section, said coded energy supply circuit being complete when the contacts of said track relay remain in their released position for a predetermined time interval, a steady energy supply circuit through which steady energy may be supplied to the track rails of said rear section, and means operative on initiation of code following operation of the contacts of said track relay after the relay contacts have been released for a time interval to establish said steady energy supply circuit if and only if code following operation of said relay contacts continues after initial movement of the relay contacts to their picked up position, said means being operative to thereafter interrupt said steady energy supply circuit if and only if code following operation of the track relay continues after establishment of said steady energy supply circuit.

9. In a coded railway signaling system, in combination with adjoining forward and rear sections of railway track which are electrically separated by insulated rail joints, means for at times supplying coded energy and at other times supplying steady energy to the rails of said forward section, a code following track relay connected with the rails of said forward section, said track relay having contacts which occupy a released position when the relay winding is not energized and which are moved to a picked up position when the relay winding is energized, a first relay energized over a front contact of said track relay, a second relay energized over a back contact of said track relay provided the contacts of the first relay are picked up, a third relay energized by current supplied over a pick-up circuit which includes a front contact of said track relay provided a contact of said second relay is picked up, a fourth relay energized by current supplied over a back contact of said track relay provided a contact of said third relay is picked up, means operative on picking up of the contacts of the third relay to establish a circuit to supply steady energy to the rails of said rear section, means operative on picking up of the contacts of the fourth relay to interrupt said steady energy supply circuit, and means operative on interruption of said steady energy supply circuit for supplying coded energy to the rails of said rear section.

10. In a coded railway signaling system, in combination with adjoining forward and rear sections of railway track which are electrically separated by insulated rail joints, means for at times supplying coded energy and at other times, supplying steady energy to the rails of said forward section, a code' following track relay connected with the rails of said forward section, said track relay having contacts which occupy a released position when the relay winding is not energized and which are moved to a picked up position when the relay windingis energized, a first relay, energized over a-front contact of said track relay, asecond relay energized over a back contact of said trackrelay provided the contacts of the firstrelay are pickedup, a third relay energized by current supplied over a pick-up circuit which includesa vfrontcontact of said track relay provided va contact, of the second relay is picked up, .a fourth relay (energized by current supplied over ,a vloackvcontact of said track relay provided a contact of said third relay is picked up, means operative on picking up of the contacts of the third relay ,to establish :a circuit to supply steadyenergy to the railsiof said rear section,and means-operative on picking up of the contacts of the fourth relay to interrupt the steady energy supply circuit and to also estab'lish a circuit for supplying coded energy to the rails of the adjacent section in the rear.

-1-1. In a coded railway signaling system, in combination with adjoining forward and rear sections of railway track which are electrically separated by insulated rail joints, means for at times supplying coded energy and at other times supplying steady energy to the rails of said forwardsection, a code following track relay connected with the rails of said forward section, said track relay having movable contacts which when the relay'winding is not energized occupy a released-position in which they engage back contacts and which when therelay winding is energized occupya picked up position in which they engage front contacts, a first, a second, a third, and a fourth relay, a circuit including a front contact of the track relay and a back contact of the third relay for energizing the first relay, a circuit including back contacts of the track relay and said third relay'and a front contact of said first relay for energizing said second relay, a pick-up circuit for said third relay including front contacts of said track relay and said second relay, a holding circuit for energizing said third relay, said'holding circuit including front contacts of the track relay and of said third relay, a circuit including a back contact of the track relay and afront contact of the'third relay for energizing said fourth relay, a steady energy supply circuit including a frontcontact of the third relay and aback contact of the fourth relay for supplying steady energy to the rails of said rear section, and a coded energy supply circuit operative on interruption of said steady energy supp'ly'circuit' to supply coded energy to the rails of said rear section.

a 12. In a coded railway signaling system, in combination with adjoining forward and rear sections of railway track which are electrically separated by insulated rail joints, means for at times supplying coded energy andat other times supplying steady energy to the rails of said forward section,- a code following track relay connected with the rails of said forward section, said track relay having movable contacts which when the relay winding is not energized occupy 2. released position in which'they engage back contacts and which when the relay winding is energized occupy a picked up position in which they engage front contacts, a first, a second, a third, and a fourth relay, a circuitincludinga front contact of the track relay and a back contact of the third relay for energizing the first relay, a circuit including back contacts of the track relay and said third relay and a front contact of said first'relay for energizing said secondrelay apick-up circuit for said third relay section.

including front contacts of said track relay and said second relay, a holding circuit for energizing said third relay, said holding circuit including frontcontactsof the track relay and of said third for supplying steady energy to the rails of said rear section, and a coded energy supply circuit including a frontcontact of said fourth relay for supplying coded energy to the rails of said rear 13. In a coded combination with adjoining forward and rear sections of railway track which are electrically separated by insulated rail joints, means for at times supplying coded energy and at other times sup-plying steady energy to the rails of said forward section, a code following track relay connected with the rails of said forward section, said track relay having movable contacts which when the relay winding is not energized occupy a released position in which they engage back contacts and which when the relay winding is energized occupy apicked up position in which they engage front contacts, afirst, a second, a

third, and a fourth relay, a circuit including a front contact of thetrack relay and aback con- In. a

cluding front contacts of said track relay and said second relay, a holding circuit for energizing said third relay, said holding circuit including front contacts of the track relay and of saidthird relay, a circuit including a back contact of the track relay, and a front contact of the third re y for energizing said fourth relay, a steady energy supply circuit including a front contact of the third relay and a back contact of the fourth relay for supplying steady energy to the rails of said rear section, and a coded energysupply circuit including front contacts of saidthird and fourth relays for supplying coded energy to the rails of said rear section.

14. In a coded railwaysignaling system, in combination with adjoining forward and rear sections of railway track whichare electrically separated by insulated rail joints, means for at times supplying coded energy and at other times supplying steady energy to the rails of said forward section, a code following track relay connected with the rails of said forward section, said track relay having movable contacts which when the relay winding is not energized occupy a released position in which they engage back contacts and which when the relay winding'is energized occupy a picked up position in which they engage front contacts, a first, a second, a third, and a fourth relay, a circuit including a front contact of the track relay'and a back contact of contacts of said track relay and said-second relay, a holding circuit for energizing said third relay, said holding circuit including front contacts of the track ,relayand of said third relay, :5

a circuit including a back contact of the'track relay and a front contact of the third relay for energizing said fourth relay, a snubbing resistor operative when connected" across the winding of the third relay to render the relay contacts slow in releasing, a circuit including a front contact of said third relay for connecting said resistor across the winding of said third relay, another snubbing resistor operative when connected across the winding of the fourth relay to render the relay contacts slow in releasing, a circuit including a front contact of the third relay for connecting said other resistor across the terminals of the fourth relay, a steady energy supply circuit including a front contact of the third relay and a back contact of the fourth relay for supplying steady energy to the rails of said rear section, and a coded energy supply circuit operative 0n interruption of said steady energy supply circuit to supply coded energy tothe rails of said rear section.

15. In a coded railway signaling system, in combination with adjoining forward and rear sections of railway track which are electrically separated by insulated rail joints, means for at times supplying coded energy and at other times supplying steady energy to the rails of said forward section, a code following track relay connected with the rails of said forward section, said track relay having movable contacts which when the relay winding is not energized occupy a released position in which they engage back contacts and which when the relay winding is energized occupy a picked up position in which they engage front contacts, a first, a second, a third, and a fourth relay, a circuit including a front contact of the track relay and a back contact of the third relay for energizing the first relay, a circuit including back contacts of the track relay and said third relay and a front contact of said first relay for energizing said second relay, a pick-up circuit for said third relay including front contacts of said track relay and said second relay, a holding circuit for energizing said third relay, said holding circuit including front contacts of the track relay and of said third relay, a circuit including a back contact of the track relay and a front contact of the third relay for energizing said fourth relay, a steady energy supply circuit for supplying steady energy to the rails of said rear section, said steady energy supply circuit being established on picking up of the contacts of the third relay at a time when the contacts of the fourth relay are released and being interrupted on picking up of the contacts of the fourth relay, and a coded energy supply circuit operative on interruption of the steady energy supply circuit to supply coded energy to the rails of the rear section.

16. In a coded railway signaling system, in combination with adjoining forward and rear sections of railway track which are electrically separated by insulated rail joints, means for at times supplying coded energy and at other times supplying steady energy to the rails of said forward section, a code following track relay connected with the rails of said forward section, said track relay having movable contacts which when the relay winding is not energized occupy a released position in which they engage back contacts and which when the relay winding is energized occupy a picked up position in which they engage front contacts, a first, asecond, a third, and a fourth relay, a circuit including a front contact of the track relay and a back contact of the third relay for energizing the first -relay,..a-

first relay for energizing said second relay, a pickup circuit for said third relay including-front contacts of said track relay and said second relay, a-holding circuit for energizing said third relay, said holding circuit including front contactslof the track relay and of said third relay, acircuit including a back contact of the track relay and a front contact of the third relay for energizing said fourth relay, a steady energy supply circuit for supplying steady energyto the rails of said rear section, said steady energy supply circuit being established on picking up of the contacts of the third relay at a timezwhenthe contacts of the fourth relay are releasedand being interrupted on picking up of the contacts of the fourth relay, and means operative on release of the contacts of the third relay or on picking up of the contacts of the fourth" relay for supplying coded energy to the rails of said rear section.

1'7. In a coded railway signaling system, in combination with adjoining forward and rear sections of railway track which are electrically separated by insulated rail joints, means for at times supplying coded energy and at other times supplying steady energy to the rails of said forward section, a code following track relay connected with the rails of said forward section, said track relay having movable contacts which when the relay winding is not energized occupy a released position in which they engage back contacts and which when the relay winding is energized occupy a picked up position in which they engage front contacts, a first control relay, means controlled by contacts of .said track relay for energizing said first control relay, said means being operative to energize said control relay only when the track relay contacts are following code and being operative on initiation of code following operation of said track relay contacts to effect picking up of the contacts of said first control relay only after a plurality of movements of the track relay contacts between their two positions, a second control relay, a circuit including a back contact of the track relay and a front contact of the first control relay for energizing said sec ond control relay, a third control relay, an energizing circuit for said third control relay-including a front contact of said second control relay, a holding circuit for said first control relay including front contacts of said track relay and said first control relay and a back contact of said third control relay, a steady energy supply circuit for supplying steady energy to the rails of said rear section, said steady energy supply circuit including a front contact of said first control relay and a back contact of said second control relay, and means operative on interruption of said steady energy supply circuit to supply coded energy to the rails of said rear section.

18. In a coded railway signaling system in combination with adjoining forward and rear sections of railway track which are electrically separated by insulated rail joints, means for at times supplying coded energy and at other times supplying steady energy to the rails of said forward section, a code following track relay connected with the rails of said forward section, said track relay having movable contacts which when the relay winding is not energized occupy a released position in which they engage back contacts and which when the relay winding is energized occupy a picked up position in which they engage frontcontacts, a first control relay, means con- 

